On Mon, Jun 08, 2020 at 10:49:25AM +0800, Wang ShaoBo wrote:
> Currently arm64 personality syscall uses wrapper __arm64_sys_personality
> to redirect to __arm64_sys_arm64_personality, it's easily confused,
> Whereas using an normal hook arch_check_personality() can reject
> additional settings like this for special case of different architectures.
>
> This makes code clean and easier for subsequent modification.
Do you plan to add more stuff here? Curious what triggered this patch.
> diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
> index d5ffaaab31a7..5c01816d7a77 100644
> --- a/arch/arm64/kernel/sys.c
> +++ b/arch/arm64/kernel/sys.c
> @@ -28,12 +28,13 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long,
> len,
> return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
> }
>
> -SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
> +int arch_check_personality(unsigned int personality)
> {
> if (personality(personality) == PER_LINUX32 &&
> !system_supports_32bit_el0())
> return -EINVAL;
> - return ksys_personality(personality);
> +
> + return 0;
> }
We use the ksys_* pattern in other places as well, so this wouldn't be
something new.
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 1815065d52f3..3dbbad498027 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -1393,16 +1393,6 @@ static inline long ksys_truncate(const char __user
> *pathname, loff_t length)
> return do_sys_truncate(pathname, length);
> }
>
> -static inline unsigned int ksys_personality(unsigned int personality)
> -{
> - unsigned int old = current->personality;
> -
> - if (personality != 0xffffffff)
> - set_personality(personality);
> -
> - return old;
> -}
> -
> /* for __ARCH_WANT_SYS_IPC */
> long ksys_semtimedop(int semid, struct sembuf __user *tsops,
> unsigned int nsops,
> diff --git a/kernel/exec_domain.c b/kernel/exec_domain.c
> index 33f07c5f2515..f3682f4bf205 100644
> --- a/kernel/exec_domain.c
> +++ b/kernel/exec_domain.c
> @@ -35,9 +35,21 @@ static int __init proc_execdomains_init(void)
> module_init(proc_execdomains_init);
> #endif
>
> +int __weak arch_check_personality(unsigned int personality)
> +{
> + return 0;
> +}
> +
> SYSCALL_DEFINE1(personality, unsigned int, personality)
> {
> - unsigned int old = current->personality;
> + int err;
> + unsigned int old;
> +
> + err = arch_check_personality(personality);
> + if (err)
> + return err;
> +
> + old = current->personality;
I'm surprised that the generic sys_personality() doesn't call
ksys_personality() directly but rather duplicates the code.
Anyway, without knowing what else you plan to do with
arch_check_personality(), I don't think it's worth changing. Calling
ksys_personality() directly from sys_personality() would be a good
clean-up though.
--
Catalin
